Rotary weight-impact crushing mill



Sept. 29, 1953 N. l.. HALL ROTARY WEIGHT-IMPACT cRUsHING MILL 2sheets-shewL 1 AFiled Aug. 22, 1950 IN VEN TOR.

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Sept. 29, 1953 N. L. HALL 2,653,769

ROTARY WEIGHT-IMPACT CRUSHING MILL 2 Sheets-Sheet 2 Filed Aug. 22. 1950F' 11) INVENToR.

Patented Sept. 29,

UNITED PATENT OFFICE yzsarsa ROTARY WEIGHT-IMPACT citUsHING MILL Nwfn L.Hall, Lons Bwhycat- Application Augustz, 1950, Serial Nd. *180,752

This invention relates to rotary .crushingior pulverizing mills used forthe `crushing or fine grinding of ores, cement, ,or `other granular ma,-terial,

Under the trade name Yof rotary impact;crush-r ing mill it is used forthe crushing, grindingor comminuting of rocks, the dressing, of ores,.orthe ne grinding of materials tov a' dry powder, or a wet pulp, andwherein a load ofA primarily crushed rock or material is freelyy tumbledin: a revolving cylinder of longitudinal .compartment design to developits` secondary crushing .or ii'ner grinding with a crushing mediumofconcentrated load-weights, oneV for .each .,compartment,l freelytumbling within the mill. l,and its'load to assist in the comminutingoperation. c

In this class of mills. the loadv is .subject to a tumbling action orfalling in a. -drumor other rotating receptacle as distinguished from.ma.- chines in which the*y material' isr broken v.up by' the crushingAaction .of stamps, rolls,v jaws, or `simi.- lar crushing elements.

One of the objects of the invention is to :proevide a rotary mill withconcentrated'loadweights to develop an internal ,crushingactionwithinfthe load, and, between the load-weight and the mill shell andcompartment wall.

Another object of the invention is, to-concerL-f trate the crushingvmedium into a compactibod'y of considerable weight and toeliminate theuse of crushing media `of comparatively `smallusizeunits of light weightthereby GQncentrating .and enlarging the effective crushing uaction andv,raducing the extent of' wearingsurface expoedvgto crushing action andwear on both'gthe ,crushing media, the mill shell lining,v and onthegcompartment wall.

Another object of the invention is, to provide:

a rotary mill with longitudinal loagiwsightsy which effectively advancethe transientn3-aterialA passing through the mill by Virtuepf the load;-weight shape and falling action.

Other objects of theA :invention will' become? apparent as the inventionis` disclosed..

This invention consistsv in. the details 'of :con-V struction, and thearrangementiand.combination of the several parts ofV myimprovedirotary'irn-r In the lfollowing ydescriptions reference iis-made f to the accompanying drawings wherein: y

Figure 1 is a longitudinallvertical sectionoa rotary mill, taken onlineile-,I of; Figure 2r.and;

embodying one yform .of .my invention;

Figure 2 is av crossA section of a Irotary mill taken online 2-2 ofFigure 1 and showing the driving gears in partial cut;

Figure 3 is a side elevation of ra load-Weight i of a twin cylinder of adumb bell type;

Figur'e is a diagrammatic crossr section of the Y cylinder of -acompartment mill with the compartment -Wallin ahorizontal position as itwould bev in' starting,` andi wjth the load and load-weight shown inieach compartment;

Figure' 7 .is a diagrammatic cross section of the cylinder of acompartment mill, similar to Figure 6, with thelcompartment walll in avertical position and' withthe load and load-weights in av lowered`position,--the mill advance being noted in .each yView from vtheposition of the arrows A;

Figure 87.is a` diagrammatic Across section of the cylinder .of alcompartment mill, lsimilar to Figure 7, with the compartment wall shownin an advanced ,position andk withvthe load and loadweights having .beencarried towards the zenith of the. mill `interior `and prior to thefalling of the loads from :theirl positions;

Figure. 9 isa .diagrammatic cross section of the `cylinder of acompartment null, similar to Figure' 8,'withi the compartment wall in afurther advanced .positionaand with the rearward load andY load-.weightvvhaving fallen to a lower position .priorto -.thefallingof the liorwardload vand load-weight and which follows in sequence, the milladvancebeing'notedfrom-.the -position of the arrow A.; f

Figure l0 is a diagrammatic cross section of the ycylinder .of a:compartment mill, with the same .loadeweight yshown .in variouspositions, without vthe load, and showing `the orbit of a single,load-weight passing through one` revolution .off .the zmill;

-Eigure-1f1fisia .diagrammatic cross section of the cylinderofalcompartmentmill, showing the compartment wall in' dotted lines =for`position when Lther.rezairwaaadrload `takes its first fall, iol-y lowedby an advanced position of the wall in 'full' lines;Whereuponxthewiorward .load .takes 4its fall secondly, the sections ofithe view being shown withoutnthe load;

.Similarl reerenCe'icharaGter-s refer to similarpartswin;allottheiviewsi` In the description herein used the termffcom-.Apartment:millfspecificallyapplies to amillV with its interior dividedinto two semi-cylindrical and longitudinal compartments, formed byvirtue of a diametral wall extending from side to side of the millinterior, and substantially the full length of the mill, such a wallrevolving with the mill shell and effecting the characteristiccompartment mill action. Compartments of other cross section, developinga similar action, could be used without departing from the spirit of theinvention.

As used herein, the teirn load refers to the material being ground. Theterm load-weight refers to the concentrated crushing medium or cylinderas used in the current descriptions.

The term mill load refers to the combined load within the mill includingboth the material being ground and the grinding media.

Referring to the drawings:

Figure l is a longitudinal vertical section of a mill embodying one formof my invention wherein the cylindrical mill shell I has heads 2 whichare attached thereto by the bolts 3, and having integral therewithhollow trunnion bearings 4 which rotate in the supporting bearings 5,the

cylinder as a unit being revolved by the drive i gear 6 which in turn isactuated by the pinion I and which is motivated by the drive shaft 8from any suitable motive power; see Figure 2.

The hollow trunnion 4 at the feed end of the cylindrical mill is fed bymeans of the scoop 9 which discharges its load into the hollow trunnionwhere it is advanced by the internal thread l which revolves with themill trunnion 4. At the discharge end of the mill, the discharge trunion4 with its screen grate Ia grades the circulating load in its advanceand discharge from the mill.

The mill shell has protecting liners on its interior, for the heads II,and for the cylindrical shell I2. Extending diametrally across the millfrom wall to wall, a compartment Wall I3 extends substantially from headto head of the mill dividing the mill interior into two semi-cylindricalcompartments.

At the feed end of the mill the compartment wall is recessed at i4 toprovide for a better distribution of the entering and advancing feed. Atthe discharge end of the mill the Wall is discontinued to provide spacel for a combination of the loads from each compartment prior to theirpassing through the grate Illa and the discharge trunnion 4. Thediametral compartment wall is opened by the space I6 which effects aclear and open slot provision extending from wall to Wall of the millshell and provides for a free and unobstructed passage of a portion ofthe load to equalize the loads on each side of the compartment wallduring action.

As shown in Figures 1 and 2, a circulating load carries within it anelongated cylindrical loadweight l1, substantially the length of themill interior, one for each compartment and which move freely within therespective load as the mill is revolving under action. For the purposeof varying the weight of this load-weight, it is formed hollow and theweight can be varied by loading Within its interior i8, liquid as l8a,through the plugged vent I9.

The load-weight as shown in Figure 3 is formed of two similar cylindersI'Ia and lla', rigidly connected at the neck llb to act as one body, andprovides for a contracted opening at the neck to co-act on the loadthrough the open space of the wall I6.

The load-weight as shown in Figure 4 is formed of varying cross section,one as a true cylinder lla, and the other as a truncated cone llc, beingrigidly connected at the neck Hb. The conical shape of the load-weightin falling has a resultant thrust upon the load parts and the cone canbe used to advance such parts in one direction, or retard them to theopposite direction as the load parts are migrating through the mill.

As shown in Figure 5, the cross section of a weight cylinder has ribbedprojections Hd, and the exterior portions near the surface of theloadweight can be hardened as at I'le to improve its wearing qualities.The load-weight can be of any suitable cross section to engage andconfine the load to produce an effective crushing action.

As shown in Figure 10, the orbit of one loadweight during one revolutionof the mill: The position of the wall in starting being the same as forFigure 9 with the load-weight D-l falling through the orbit or path P-lto the position D-2, then ascending through the path P-2 to the positionD-3 (the position of the wall as shown being disregarded) then fallingthrough the path P-3 to the position D-4, then ascending through thepath P-4 to the position D-I, the place of beginning,

As shown in Figure 1l, with one load-weight in each compartment, andwith the position of the compartment wall as shown in dotted lines; theload-weight E takes a first fall to the position E', and with theadvance of the wall to the position as shown in full lines, theload-weight F follows with a fall to the position F'. Each load andload-weight in falling-following the advancing Wall in itsrotation-falls first in a short fall rearward of the compartment wall,followed by a fall of the load and load-weight forward of the wall intoa longer fall. Each half load with its loadweight receives two falls foreach revolution of the mill, one as it follows the wall in a short fall,and then as it is carried to the zenith of the mill interior, in alonger fall on the side in advance of the compartment wall.

Referring to a mill of a full cylindrical cross section and without adiametral wall as a plain mill: A concentrated load-weight within afreely tumbling load of a plain mill will vary its positions within theload, for its position is uncontrolled and the center of gravity of suchan erratic load is constantly changing position and may be anywherewithin the mill-load. The motive power applied to a plain mill with ahomogeneous load is constantly being influenced by irregularities of themill-load in its positions and the revolving mill-load with its crest incascade does not place a uniform resistance upon the motivating power.Placing a concentrated loadweight within such a load exaggerates theconditions, for the load-weight can take any position within or on theload and do so without control, and the position of the center ofgravity of the revolving load and load-weight is variable and constantlywithout control.

The use of a compartment mill with its diametral wall and divided loadand load-weights changes the fundamental conditions of action; Althoughthe load-weight is freely tumbling the compartment wall controls itsposition and it does not have an unrestricted freedom of action, and ifthe load and load-weights are correctly proportioned for size andweight, the load-weight will retain its position submerged within theload and in action the load-weight will seldom strike the mill shell ordiametral wall and a cushion of a part of the load will be in advanceand positioned between the load-,weight and the shell, .or

wall. e

The compartment mill necessitates that the mill load take two falls foreach revolution of the mill and in so doing, parts of the load Will fallahead of the load-weight and be in position to reoeive and cushion theload-weight in its fall, and the fallen load will receive theconcentrated crushing action between the load-weight and the mill shell,or, compartment wall. As shown in Figure 8, that portion of the loadwhich has fallen, as l'lf, will be in position to receive the loadweightB in falling, receiving a crushing action between the load-weight andthe mill shell, and to the fallen position of the load-Weight B as shownin Figure 9. The Wall and mill being advancedto the position as shown inFigure 9, a portion of the load Hg, having fallen in advance to receivethe load-weight C, develops a similar crushing action on the loadbetween the load- Weight and the mill shell.

As characteristic of the compartment mill, the compartment wall providesthe lifting provision for the load and no internal shell projections forlifters for engaging the load are required, thereby allowing the fulltransverse dimension of the mill section to be available for effectivemill load action.

Mills which use small balls or slugs intermixed as a grinding mediawithin the load, act without a control of the mill load parts and theballs can strike in any direction and wear on other balls, or, on themill lining, and do so indiscriminately without developing any effectivecrushing action on the material to be ground, accordingly, and unlessmaterial to be crushed is positioned between the steel parts, such workis wearing on the steel parts without a grinding effect on the material.

The compartment mill can have its mill load adjusted to suit the densityof the material to be ground and when properly adjusted for size andweight, the load-weight can be maintained submerged within the materialload so that the full action of the load-weight can be exerted incrushing the material in which it is submerged. When under rotation, anyirregularity of the centers of gravity of the load parts is balanced andabsorbed within the weight of the mill structure. The mill load of onecompartment is balanced over the mill supports by the mill load of thecorresponding compartment.

The load-weight is preferably cylindrical, of a hardened or tough steelsurface capable of resistance to wear and presents a concentrated weightto develop an enlarged and effective crushing force on the load, and byvirtue of its position control as offered by the compartment millfeature, the weight can be submerged within the load by further virtueof its variable weight to produce a concentrated crushing actioninternal to the load and do so without bringing the crushing medium intocontact with the mill shell or its parts and avoid non-essentialcontacts with their destructive wear.

The mill load can be a combination of materials to be ground, intermixedwith grinding balls if desirable to form a secondary grinding media,combined with the load-weights for forming the primary grinding media.

As the load of each compartment falls it changes position with thecontained air within the compartment and in addition to the crushingactions as described, the intermixing air can float and carry insuspension the extreme fines and 6i' fibres ofthe load by an air sweptsystem for removal from the mill.

i The load-weight can be of various shapes. and sizes to develop thedesired result when falling upon or within the mill-load, or load. Theweight can be formed with various cross sections so that in falling uponthe load ity can advance or retard the parts of the load as desired byvirtue of the resultant thrust as induced by the shape of theload-Weight.

The effective crushing action of the falling concentrated load-weightupon the load can develop an enlarged crushing or impact action, and byreason of the load-Weight being submerged Within the load and notstriking the mill shell or Wall, an enlarged impact is produced incrushing the material than would be the case wherein a mass oi smallballs were used as a crushing media, accordingly', the range of size forthe mill feed can be decidedly changed or enlarged, the result beingaccomplished with an economy of steel wear upon the mill parts.

In the conventional plain mill using small balls as a grinding mediawithin a mill load and grinding a wet pulp, clean washed balls are notas effective in grinding as when using a pulp of lower moisture contentthereby developing a muddy coating to the ball whereby the pulp sticksto the ball and is held in position to receive the contacting impact ofadjoining and cascading balls, and thus a load pulp can be of too high amoisture content for effective grinding.

In the compartment mill using a load-weight within the mill load, thecrushing or grinding action of the load-Weight upon the load isindependent of the moisture condition of the load pulp and an effectivecrushing action is developed by the load-weight in falling upon theload, regardless of the moisture content of the load.

l. claim:

1. In combination: a horizontal rotary mill comprising; a cylindricalcasing having openings at both ends for receiving and dischargingmaterial; and a wall within the casing lying substantially in adiametral plane and extending across the full diametral width of thecasing and longitudinally for a major portion of the length of thecasing to divide the interior thereof into two compartments; said wallbeing provided with an opening intermediate its ends extending acrossthe full diametral width of the casing to provide for free passage ofmaterial by gravity through said opening from each compartment to theother, and a single elongated cylindrical major load-weight extendingapproximately the full length of and in each of said compartments, saidload-weights having intermediate sections of reduced diameters spaced inconformity with said intermediate openings 0f said wall to provide aco-action within and between the said materials passing through saidopenings during rotation of the mill.

2. A horizontal rotary mill comprising: a cylindrical casing mounted forrotation about its longitudinal axis; a Wall within the casing lyingsubstantially in a diametral plane and extending across the fulldiametral Width of the casing and longitudinally for the major portionof the length of the casing to divide the interior thereof in to twosubstantially semi-cylindrical compartments; and a single majorload-Weight disposed in each of said compartments and free to movetherein upon rotation of the casing, each of said loadweights extendinglongitudinally for a greater portion of the length of the casing.

3. A horizontal rotary mill comprising: a cylindrical casing mounted forrotation about its 1ongitudinal axis; a wall Within the casing lyingsubstantially in a diametral plane and extending across the fulldiametral width of the casing and longitudinally for a major portion ofthe length of the casing to divide the interior thereof into twosubstantially semi-cylindrical compartments; said wall being providedwith an opening intermediate its ends and extending across the fulldiametral width of the casing to provide for free passage of material individed condition by gravity through said opening from each compartmentto the other upon rotation of the casing; and a single major load-weightdisposed in each of said compartments and free to move therein uponrotation of the casing, each of said load-weights extendinglongitudinally for a greater portion of the length of the casing andextending across said opening and projecting beyond the position of saidopening toward each end of the casing so as to be retained in itsrespective compartment.

NEWTON L. HALL.

References Cited in the le of this patent UNITED STATES PATENTS NumberNumber Name Date Close Mar. 10, 1891 Moussette Feb. 24, 1914 Hall Sept.9, 1919 Eggert Mar. 27, 1923 Cramm Nov. 25, 1924 Goebels Nov. 22, 1927Scherbaum Jan. 17, 1928 Rexworthy Aug. 23, 1932 McMillan May 2, 1933Price Dec. 26, 1939 Hall Jan. 1, 1952 FOREIGN PATENTS Country Date GreatBritain Aug. 24, 1911 Great Britain of 1929 Germany Nov. 11, 1938

